//public class mysql {
//}
//
//
//Enter password: *********
//Welcome to the MySQL monitor.  Commands end with ; or \g.
//Your MySQL connection id is 8
//Server version: 8.0.39 MySQL Community Server - GPL
//
//Copyright (c) 2000, 2024, Oracle and/or its affiliates.
//
//Oracle is a registered trademark of Oracle Corporation and/or its
//affiliates. Other names may be trademarks of their respective
//owners.
//
//        Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
//
//mysql> select null = null;
//        +-------------+
//        | null = null |
//        +-------------+
//        |        NULL |
//        +-------------+
//        1 row in set (0.00 sec)
//
//mysql> select 1 <=> 1;
//        +---------+
//        | 1 <=> 1 |
//        +---------+
//        |       1 |
//        +---------+
//        1 row in set (0.00 sec)
//
//mysql> select 1 <=> 2;
//        +---------+
//        | 1 <=> 2 |
//        +---------+
//        |       0 |
//        +---------+
//        1 row in set (0.00 sec)
//
//mysql> select null <=> null;
//        +---------------+
//        | null <=> null |
//        +---------------+
//        |             1 |
//        +---------------+
//        1 row in set (0.00 sec)
//
//mysql> select null != null;
//        +--------------+
//        | null != null |
//        +--------------+
//        |         NULL |
//        +--------------+
//        1 row in set (0.00 sec)
//
//mysql> select 2 between 1 and 3;
//        +-------------------+
//        | 2 between 1 and 3 |
//        +-------------------+
//        |                 1 |
//        +-------------------+
//        1 row in set (0.00 sec)
//
//mysql> select 1 in (1,2,3,4,5);
//+------------------+
//        | 1 in (1,2,3,4,5) |
//        +------------------+
//        |                1 |
//        +------------------+
//        1 row in set (0.00 sec)
//
//mysql> select 1 in (2,3,4,5);
//+----------------+
//        | 1 in (2,3,4,5) |
//        +----------------+
//        |              0 |
//        +----------------+
//        1 row in set (0.00 sec)
//
//mysql> use test;
//Database changed
//mysql> select * from score;
//+----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  1 | 唐三藏    |    67.0 | 98.0 |    56.0 |
//        |  2 | 孙悟空    |    87.5 | 78.0 |    77.0 |
//        |  3 | 猪悟能    |    88.0 | 98.0 |    90.0 |
//        |  4 | 曹孟德    |    82.0 | 84.0 |    67.0 |
//        |  5 | 刘玄德    |    55.5 | 85.0 |    45.0 |
//        |  6 | 孙权      |    70.0 | 73.0 |    78.5 |
//        |  7 | 宋公明    |    75.0 | 65.0 |    30.0 |
//        |  8 | 孙行者    |    87.5 | 78.0 |    77.0 |
//        +----+-----------+---------+------+---------+
//        8 rows in set (0.00 sec)
//
//mysql> select * from score where chinese > english;
//+----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  1 | 唐三藏    |    67.0 | 98.0 |    56.0 |
//        |  2 | 孙悟空    |    87.5 | 78.0 |    77.0 |
//        |  4 | 曹孟德    |    82.0 | 84.0 |    67.0 |
//        |  5 | 刘玄德    |    55.5 | 85.0 |    45.0 |
//        |  7 | 宋公明    |    75.0 | 65.0 |    30.0 |
//        |  8 | 孙行者    |    87.5 | 78.0 |    77.0 |
//        +----+-----------+---------+------+---------+
//        6 rows in set (0.00 sec)
//
//mysql> select * from score where chinese > 80 or english > 80;
//        +----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  2 | 孙悟空    |    87.5 | 78.0 |    77.0 |
//        |  3 | 猪悟能    |    88.0 | 98.0 |    90.0 |
//        |  4 | 曹孟德    |    82.0 | 84.0 |    67.0 |
//        |  8 | 孙行者    |    87.5 | 78.0 |    77.0 |
//        +----+-----------+---------+------+---------+
//        4 rows in set (0.00 sec)
//
//mysql> select * from score where chinese > 80 0r math > 70 and english > 70;
//ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '0r math > 70 and english > 70' at line 1
//mysql> select * from score where chinese > 80 or math > 70 and english > 70;
//        +----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  2 | 孙悟空    |    87.5 | 78.0 |    77.0 |
//        |  3 | 猪悟能    |    88.0 | 98.0 |    90.0 |
//        |  4 | 曹孟德    |    82.0 | 84.0 |    67.0 |
//        |  6 | 孙权      |    70.0 | 73.0 |    78.5 |
//        |  8 | 孙行者    |    87.5 | 78.0 |    77.0 |
//        +----+-----------+---------+------+---------+
//        5 rows in set (0.00 sec)
//
//mysql> select * from score where chinese between 80 and 90;
//        +----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  2 | 孙悟空    |    87.5 | 78.0 |    77.0 |
//        |  3 | 猪悟能    |    88.0 | 98.0 |    90.0 |
//        |  4 | 曹孟德    |    82.0 | 84.0 |    67.0 |
//        |  8 | 孙行者    |    87.5 | 78.0 |    77.0 |
//        +----+-----------+---------+------+---------+
//        4 rows in set (0.00 sec)
//
//mysql> select * from score where chinese >= 80 and chinese <= 90;
//        +----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  2 | 孙悟空    |    87.5 | 78.0 |    77.0 |
//        |  3 | 猪悟能    |    88.0 | 98.0 |    90.0 |
//        |  4 | 曹孟德    |    82.0 | 84.0 |    67.0 |
//        |  8 | 孙行者    |    87.5 | 78.0 |    77.0 |
//        +----+-----------+---------+------+---------+
//        4 rows in set (0.00 sec)
//
//mysql> select * from score where math = 58 or math = 59 or math = 98 or math = 99;
//+----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  1 | 唐三藏    |    67.0 | 98.0 |    56.0 |
//        |  3 | 猪悟能    |    88.0 | 98.0 |    90.0 |
//        +----+-----------+---------+------+---------+
//        2 rows in set (0.00 sec)
//
//mysql> select * from score where math in (58, 59, 98, 99);
//+----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  1 | 唐三藏    |    67.0 | 98.0 |    56.0 |
//        |  3 | 猪悟能    |    88.0 | 98.0 |    90.0 |
//        +----+-----------+---------+------+---------+
//        2 rows in set (0.00 sec)
//
//mysql> select * from scorel;
//ERROR 1146 (42S02): Table 'test.scorel' doesn't exist
//mysql> select * from score;
//+----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  1 | 唐三藏    |    67.0 | 98.0 |    56.0 |
//        |  2 | 孙悟空    |    87.5 | 78.0 |    77.0 |
//        |  3 | 猪悟能    |    88.0 | 98.0 |    90.0 |
//        |  4 | 曹孟德    |    82.0 | 84.0 |    67.0 |
//        |  5 | 刘玄德    |    55.5 | 85.0 |    45.0 |
//        |  6 | 孙权      |    70.0 | 73.0 |    78.5 |
//        |  7 | 宋公明    |    75.0 | 65.0 |    30.0 |
//        |  8 | 孙行者    |    87.5 | 78.0 |    77.0 |
//        +----+-----------+---------+------+---------+
//        8 rows in set (0.00 sec)
//
//mysql> select * from score where chinese is not null;
//        +----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  1 | 唐三藏    |    67.0 | 98.0 |    56.0 |
//        |  2 | 孙悟空    |    87.5 | 78.0 |    77.0 |
//        |  3 | 猪悟能    |    88.0 | 98.0 |    90.0 |
//        |  4 | 曹孟德    |    82.0 | 84.0 |    67.0 |
//        |  5 | 刘玄德    |    55.5 | 85.0 |    45.0 |
//        |  6 | 孙权      |    70.0 | 73.0 |    78.5 |
//        |  7 | 宋公明    |    75.0 | 65.0 |    30.0 |
//        |  8 | 孙行者    |    87.5 | 78.0 |    77.0 |
//        +----+-----------+---------+------+---------+
//        8 rows in set (0.00 sec)
//
//mysql> select * from scoer limit 2;
//ERROR 1146 (42S02): Table 'test.scoer' doesn't exist
//mysql> select * from score limit 2;
//        +----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  1 | 唐三藏    |    67.0 | 98.0 |    56.0 |
//        |  2 | 孙悟空    |    87.5 | 78.0 |    77.0 |
//        +----+-----------+---------+------+---------+
//        2 rows in set (0.00 sec)
//
//mysql> select * fromm score limit 0, 2;
//ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'fromm score limit 0, 2' at line 1
//mysql> select * from score limit 0, 2;
//        +----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  1 | 唐三藏    |    67.0 | 98.0 |    56.0 |
//        |  2 | 孙悟空    |    87.5 | 78.0 |    77.0 |
//        +----+-----------+---------+------+---------+
//        2 rows in set (0.00 sec)
//
//mysql> select * from score limit 0, 2;
//        +----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  1 | 唐三藏    |    67.0 | 98.0 |    56.0 |
//        |  2 | 孙悟空    |    87.5 | 78.0 |    77.0 |
//        +----+-----------+---------+------+---------+
//        2 rows in set (0.00 sec)
//
//mysql> select * from score limit 2 offest 0;
//ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'offest 0' at line 1
//mysql> select * from score limit 2 offset 0;
//        +----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  1 | 唐三藏    |    67.0 | 98.0 |    56.0 |
//        |  2 | 孙悟空    |    87.5 | 78.0 |    77.0 |
//        +----+-----------+---------+------+---------+
//        2 rows in set (0.00 sec)
//
//mysql> select * from score limit 2, 2;
//        +----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  3 | 猪悟能    |    88.0 | 98.0 |    90.0 |
//        |  4 | 曹孟德    |    82.0 | 84.0 |    67.0 |
//        +----+-----------+---------+------+---------+
//        2 rows in set (0.00 sec)
//
//mysql> select * from score limit 4, 2;
//        +----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  5 | 刘玄德    |    55.5 | 85.0 |    45.0 |
//        |  6 | 孙权      |    70.0 | 73.0 |    78.5 |
//        +----+-----------+---------+------+---------+
//        2 rows in set (0.00 sec)
//
//mysql> update score set math = 80 where name = '孙悟空';
//Query OK, 1 row affected (0.01 sec)
//Rows matched: 1  Changed: 1  Warnings: 0
//
//mysql> select * from score;
//+----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  1 | 唐三藏    |    67.0 | 98.0 |    56.0 |
//        |  2 | 孙悟空    |    87.5 | 80.0 |    77.0 |
//        |  3 | 猪悟能    |    88.0 | 98.0 |    90.0 |
//        |  4 | 曹孟德    |    82.0 | 84.0 |    67.0 |
//        |  5 | 刘玄德    |    55.5 | 85.0 |    45.0 |
//        |  6 | 孙权      |    70.0 | 73.0 |    78.5 |
//        |  7 | 宋公明    |    75.0 | 65.0 |    30.0 |
//        |  8 | 孙行者    |    87.5 | 78.0 |    77.0 |
//        +----+-----------+---------+------+---------+
//        8 rows in set (0.00 sec)
//
//mysql> update score set math = 60, chinese = 70 where name = '曹孟德';
//Query OK, 1 row affected (0.01 sec)
//Rows matched: 1  Changed: 1  Warnings: 0
//
//mysql> select * from score;
//+----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  1 | 唐三藏    |    67.0 | 98.0 |    56.0 |
//        |  2 | 孙悟空    |    87.5 | 80.0 |    77.0 |
//        |  3 | 猪悟能    |    88.0 | 98.0 |    90.0 |
//        |  4 | 曹孟德    |    70.0 | 60.0 |    67.0 |
//        |  5 | 刘玄德    |    55.5 | 85.0 |    45.0 |
//        |  6 | 孙权      |    70.0 | 73.0 |    78.5 |
//        |  7 | 宋公明    |    75.0 | 65.0 |    30.0 |
//        |  8 | 孙行者    |    87.5 | 78.0 |    77.0 |
//        +----+-----------+---------+------+---------+
//        8 rows in set (0.00 sec)
//
//mysql> update score set math + 30 order by math acs limit 3;
//ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '+ 30 order by math acs limit 3' at line 1
//mysql> update score set math = math + 30 order by math asc limit 3;
//ERROR 1264 (22003): Out of range value for column 'math' at row 3
//mysql> update score set math = math - 30 order by math asc limit 3
//        -> ;
//Query OK, 3 rows affected (0.01 sec)
//Rows matched: 3  Changed: 3  Warnings: 0
//
//mysql> select * from score order by math asc;
//+----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  4 | 曹孟德    |    70.0 | 30.0 |    67.0 |
//        |  7 | 宋公明    |    75.0 | 35.0 |    30.0 |
//        |  6 | 孙权      |    70.0 | 43.0 |    78.5 |
//        |  8 | 孙行者    |    87.5 | 78.0 |    77.0 |
//        |  2 | 孙悟空    |    87.5 | 80.0 |    77.0 |
//        |  5 | 刘玄德    |    55.5 | 85.0 |    45.0 |
//        |  1 | 唐三藏    |    67.0 | 98.0 |    56.0 |
//        |  3 | 猪悟能    |    88.0 | 98.0 |    90.0 |
//        +----+-----------+---------+------+---------+
//        8 rows in set (0.00 sec)
//
//mysql> update score set math = math + 30 order by math asc;
//ERROR 1264 (22003): Out of range value for column 'math' at row 4
//mysql> update score set math = math + 30 order by math asc limit 3;
//Query OK, 3 rows affected (0.01 sec)
//Rows matched: 3  Changed: 3  Warnings: 0
//
//mysql> update score set math = math + 30 order by (chinese + math + english) asc limit 3;
//ERROR 1264 (22003): Out of range value for column 'math' at row 2
//mysql> update score set math = math - 30 order by (chinese + math + english) asc limit 3;
//Query OK, 3 rows affected (0.01 sec)
//Rows matched: 3  Changed: 3  Warnings: 0
//
//mysql> select * from scorel
//    -> ^C
//mysql> select * from score;
//+----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  1 | 唐三藏    |    67.0 | 98.0 |    56.0 |
//        |  2 | 孙悟空    |    87.5 | 80.0 |    77.0 |
//        |  3 | 猪悟能    |    88.0 | 98.0 |    90.0 |
//        |  4 | 曹孟德    |    70.0 | 30.0 |    67.0 |
//        |  5 | 刘玄德    |    55.5 | 55.0 |    45.0 |
//        |  6 | 孙权      |    70.0 | 73.0 |    78.5 |
//        |  7 | 宋公明    |    75.0 | 35.0 |    30.0 |
//        |  8 | 孙行者    |    87.5 | 78.0 |    77.0 |
//        +----+-----------+---------+------+---------+
//        8 rows in set (0.00 sec)
//
//mysql> update score set chinese = chinese * 2 where chinese < 50;
//Query OK, 0 rows affected (0.00 sec)
//Rows matched: 0  Changed: 0  Warnings: 0
//
//mysql> select * from score;
//+----+-----------+---------+------+---------+
//        | id | name      | chinese | math | english |
//        +----+-----------+---------+------+---------+
//        |  1 | 唐三藏    |    67.0 | 98.0 |    56.0 |
//        |  2 | 孙悟空    |    87.5 | 80.0 |    77.0 |
//        |  3 | 猪悟能    |    88.0 | 98.0 |    90.0 |
//        |  4 | 曹孟德    |    70.0 | 30.0 |    67.0 |
//        |  5 | 刘玄德    |    55.5 | 55.0 |    45.0 |
//        |  6 | 孙权      |    70.0 | 73.0 |    78.5 |
//        |  7 | 宋公明    |    75.0 | 35.0 |    30.0 |
//        |  8 | 孙行者    |    87.5 | 78.0 |    77.0 |
//        +----+-----------+---------+------+---------+